Based on the finite element software ETABS, the effect of outriggers on the seismic response of a 50-story steel frame-reinforced concrete core tube structure was analyzed in this paper. Periods of free-vibrations were obtained from mode analysis. Response spectrum on the seismic properties was discussed. Elastic time history method was used to get complete analysis of the structure adopting four seismic waves. Structural horizontal displacement, drift angle, internal force of components and the distribution of internal forces between inner tube and outer frame under earthquake were studied. The rational quantity and locations of outriggers were considered. Further research in elastic time history was presented considering the influence of quantity of outriggers when outriggers were all set in “reasonable locations”. Some suggestions about steel frame-reinforced concrete core tube structures with outriggers in earthquake areas were given.